Currently, at the level of a dashboard, the information displays necessary for driving a motor vehicle (running speed, engine rotation speed, fuel level, . . . ) are increasingly in a virtual format (that is to say as images) via a reconfigurable screen, comprising an active matrix, generally of the Thin Film Transistor (TFT) type.
These TFT screens can usually be used simultaneously to display a GPS map provided by a browser, in a specific region or in the background.
In addition, the dashboard generally also has warning or alarm warning lights, which can be made separately and independently of such a screen (in the form of LED lights or display screens), either integrated into the TFT screen as icons that may selectively appear on the display surface, in strong contrast with the bottom of the screen.
Such a display screen generally comprises at least one active zone whose pixels are used, permanently or occasionally at least, for the display of said instrument cluster, and possibly a map, and the display of one or more warning or alarm icon(s), optionally inlaid in the instrument cluster and/or the map, the screen also comprising at least one dead zone, the pixels of which are never used for displaying the instrument cluster or the map, or for the display of icon(s).
When serving to give directions and safety information, the display of the icons must be guaranteed.
However, for separate indicator lamps it is only necessary to control their power supply to determine their operating status. Such verification, which would ensure the correct display of an embedded icon, is impossible with active matrix displays (TFT).
Indeed, a good power supply, or even an adequate operation of the control circuits of the region(s) of the screen assigned(s) to the display of the icon(s), does not guarantee that the latter are actually visible on the screen when they should be.
Moreover, the manufacturers of such screens do not provide any guarantee as to the information displayed, but only as to the correct operation of the screen control.
In an attempt to overcome this limitation, checking the content of the display of such screens before their installation has been proposed, by means of a system comprising a plurality of cameras arranged opposite the screen and revealing each display of information in a particular region of this screen. A comparison is made between the content of the image whose display has been ordered for a region in question and the content of the image revealed by the camera associated with this region, and the quality of the screen's operation is deduced therefrom and from its control in this manner during the aforementioned testing phase (see “Putting instrument panel through their paces”, Paul Jones, Vision Systems Design, Jan. 14, 2014).
However, this known system is complex and expensive, and the verification process tedious. In addition, this test can be performed on-board and is performed only once before installation in situ of the screen, in connection with a specific display setting.